Keyser signed a one-year contract with the Kunlun Red Star of the KHL on Thursday.
Keyser was put on waivers Monday for the purpose of assignment to AHL Providence.
Keyser signed a one-year, two-way contract worth $775,000 at the NHL level with Boston on Wednesday, per CapFriendly.
Keyser was returned to AHL Providence on Monday.
Keyser was assigned to AHL Providence on Saturday.
Keyser was called up by Boston on Wednesday, per Mark Divver of the New England Hockey Journal.
Keyser signed a one-year, two-way contract with Boston on Tuesday.
Keyser rejoined the taxi squad Thursday, per CapFriendly.
Keyser was Mark Divver of the New England Hockey Journal to AHL Providence from the taxi squad Thursday.
Keyser was added to the taxi squad from AHL Providence on Tuesday, Matt Porter of The Boston Globe reports.