Goodwill as of June 30, 2021 and 2020 and changes in the carrying amount of goodwill for the respective periods are as follows (in thousands):

	As of June 30,
	2021		2020
Balance at the beginning of the period	$	57,717	$	57,770
Currency translation adjustment		243		(53	)
Balance at the end of the period	$	57,960	$	57,717

In fiscal year 2021, the Company performed its annual goodwill impairment test and determined that there was no impairment to goodwill. The Company will continue to monitor its recorded goodwill for indicators of impairment.

The Company’s intangible assets associated with purchased patent license are as follows (in thousands):

		As of June 30, 2021							As of June 30, 2020
	Useful Lives	Gross Carrying Amount		Accumulated Amortization			Net Amount		Gross Carrying Amount		Accumulated Amortization			Net Amount
	(in years)
Patent license	2 - 7	$	1,170	$	(735	)	$	435	$	1,170	$	(507	)	$	663

During fiscal year 2017, the Company purchased a patent license with a useful life of seven years. During the fiscal year 2020 the Company purchased a patent license for $170 thousand with a useful life of two years. The Company did not identify any triggering events that would indicate potential impairment of its definite‑lived intangible and long‑lived assets as of June 30, 2021 and 2020.

Amortization expense related to purchased intangible assets was $0.2 million, $0.2 million and $0.1 million for the years ended June 30, 2021, 2020 and 2019, respectively.

The estimated future amortization expense of purchased intangible assets as of June 30, 2021 is as follows (in thousands):

Year Ending June 30,	Amount
2022	$	185
2023		143
2024		107
2025		—
	$	435