A board member with the Treasurer, Membership Director or Presidential role can set a member’s profile to be Lifetime, which will skip them for invoicing purposes. If their membership Expiration is set far into the future, effectively they are lifelong members.
Another option would be to set their membership to Complimentary and their Expiration to an appropriate time in the future. For example, if this was a Board Member receiving a single free year, the expiration should be set just one year forward.
Setting Special Cases in the Member Info page